1. Technical Field
The disclosure relates to an image control signal compensation technique for liquid crystal displays and, more particularly, to a liquid crystal display capable of improving luminance uniformity and a method of driving the same.
2. Related Art
At a certain enlarged panel size and due to the influences of temperature at high and low voltage ends and the variations of backlight luminance, human eyes may notice the phenomenon that the sides of a liquid crystal display panel are brighter while the center is dimmer at low gray scales. That is, the luminance uniformity of conventional liquid crystal display panel is not satisfactory at low gray scales. With the increase of panel size and resolution (as well as associated non-uniform variations of cell gap) and the raise of frame rate (120 Hz), the amount of data to be processed increases. Therefore, the time for data to be processed is shortened, and the resistive-capacitive loading (RC loading) in a conventional liquid crystal display panel more seriously distorts signals, resulting in a more apparent phenomenon of non-uniform luminance of the panel.
To lessen the problem of non-uniform luminance, the shape of scan waveforms can be changed. For instance, the height of scan waveforms can be lowered by reducing the gate high-voltage (VGH) to cause insufficient charging of scan drive input terminals at the sides of a panel so as to lower the luminance at the sides of the panel. However, the luminance degrees at the center and the sides of the panel are inevitably different. Moreover, this method would indirectly affect the charging of the center region. In general, the higher the gate high-voltage, the greater the drain current of the thin-film transistor (TFT), and the faster the charging speed. Therefore, the phenomenon of insufficient charging or reduced transmittance would be less likely to occur. If the gate high-voltage is lowered, the charging of the center region would be insufficient. To avoid substantially affecting the total transmittance of the whole panel, there is a certain limit to the reduction of gate high-voltage, and hence, it is difficult to satisfactorily improve the luminance uniformity.
Besides, white-tracking and over-driving can also be adjusted. Conventionally, because the luminance of a whole panel is adjusted with only a single white-tracking code and a single over-driving value, it is difficult to effectively improve the luminance uniformity of the whole panel.